Bottom-contact devices, characteristics

Fig. 15.10. Au top-contact pentacene TFT characteristics before and after parylene passivation. This device (W/L = 400/80 pm) has very similar characteristics to the bottom contact device in Fig. 15.9, suggesting degradation is not contact-related.

Typical of polymer conductors, these PEDOT-PSS electrodes exhibit an electrical conductivity of around 0.1 S/cm [11], A uniform, continuous pentacene (p-type organic semiconductor) layer is then deposited on the PEDOT-PSS source and drain electrodes to complete the bottom-contact OTFTs. Since pentacene is deposited in the final step, it is not exposed to any of the solvents (e.g., acetone) required to prepattem the PEDOT-PSS electrodes. These bottom-contact pentacene TFTs with PEDOT-PSS electrodes exhibit charge-carrier mobilities comparable to charge-carrier mobilities of typical bottom-contact pentacene TFTs with gold electrodes (0.2 cmWs) [1] and on/off current ratios as high as 10 . Eurther, these device characteristics are on par with requirements for driving most display applications [12,13]. 

Figure 17.8 Transfer characteristics of bottom-gate, bottom-contact OFET device with (a) P3FIT and (b) pBTTT semiconductor on continuous exposure to ambient, unfiltered air (c) pBTTT on continuous exposure to filtered, low humidity ( 4 % RFi) air. Reprinted with permission from M. Fieeney, C. Bailey, K. Cenevicius, M. Shkunov, D. Sparrowe, S. Tierney and i. McCulloch, Stable polythiophene semiconductors incorporating thieno[2,3-b]thiophene. J. Am. Chem. Soc., 127, 1078-1079 (2005). Copyright 2005 American Chemical Society...

Fig. 6 Left Transfer characteristics (saturation regime, Eds — —60 V) of bottom gate/bottom contact transistors with P3HT spincoated onto HMDS-treated Si02 from different boiling point solvents [chloroform, xylene, cyclohexylbenzene (CHE) and trichlorobenzene (TCB)]. Right Transconductance d/os/dEo (at Eds = V) of devices spincoated from chloroform and trichlor-...

Fig. 17.2 (a) Top-contact, bottom-gate device (b) bottom-contact, bottom-gate device (c) bottom-contact, top-gate device (d) working mechanism of a FET device with p-type materials (e) transfer characteristic curve of FET device and (f) output characteristic curve of FET device... 

Fig. 19 (a) The device schematic for a pseudo Y-junction transistor, (b) SEM micrograph of the overall circuit arrangement used in the measurement of the electrical characteristics, with Au contact pads and an FIB-patterned Pt wire contacting the Au pads and the Y-junction. (c) The ambipolar I-V curves resemble that of an n-type semiconductor at a positive gate potential, and a p-type semiconductor at a negative gate potential top), and the equivalent circuit for a pseudo Y-junction SWNT device bottom). (Reprinted with permission from [170, 171])... 

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